update notify docstrings to be more clear

[joe-p]

As a user, I found the verbage "matched items" to be rather confusing in the current documentation on the notify callback. It implies that notify is called when a match is found, but it is actually called when a candidate is pushed to the injector

[pascalkuthe]

The old doc for notify was stored accurate.

Whule notify is indeed called when an item was pushed it is also called if the matching exceeded the timeout in tick and has finished in the background. There are also other things that can trigger this. The list is intentionality not exhaustive.

Almost all information can update in the background and in that case the notification is triggered